There are many style guides on the market. When I was in the newspaper industry, the AP Stylebook (Associated Press) was the Bible. What I found confusing about the AP Stylebook was how many grammar rules we learned in school were tossed by the wayside. AP Stylebook, though, has its place in journalism.

According to Grammar Girl—Quick and Dirty Tips, the Chicago Manual of Style (Chicago or CMoS) is the oldest and largest, most comprehensive style guide. Even those in journalism often use CMoS for things AP Stylebook doesn't cover.

Chicago Manual of Style is the stylebook for book authors. It is the stylebook used by editors, mainstream and indie.

Stylebooks, however, are not rule books. Yes, they give you many grammar rules to follow, but they also give you guidelines and suggestions.

Stylebooks help you learn and to gain knowledge of grammar and writing.

The most significant use of a stylebook is to offer you a guide for consistency in your writing. Your editor will allow for leniency in your writing style, but they will probably insist on consistency. Your readers will notice if you aren't consistent... trust me on this.

There are many so-called RULES not truly set in stone—but consistency is key.